New Engine

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bikerpeter

New Member
Nov 30, 2010
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Idaho
Hello, I recently got a new Grubee Skyhawk 50cc Engine kit for Christmas. I have don't about 2 tanks on it, but am only getting up to 15mph. I have it mixed at 32:1, and everything is stock, except for a skateboard wheel chain tensioner. Every time I drive it there is a popping sound coming from the engine, and it slows down a little, but a jerky motion, and does that alot. Is the engine misfiring. Everything is going great on it, just have to make minor adjustments so it doesnt loosen. So I'm just wondering why it is going so slow and why the engine misfires or whatever it is doing. I have a 44 tooth sprocket on.
~Thanks
-Peter
zpt
 
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bikerpeter

New Member
Nov 30, 2010
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Idaho
I already have the B6HS, but we will gap it to .025. Yes, i have heard about the crappy plug cap and wire, do I just get another at any Auto parts store?
 
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bikerpeter

New Member
Nov 30, 2010
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Idaho
So why is it that I am only getting 15 mph tops, when I should get around 25mph? And I 0nly weigh 100 lbs, so the bike has no trouble pulling my weight :)
 
Venice Motor Bikes

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
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The chain is probably snagging on the teeth of the rear sprocket! (That will cause a popping sound & a slight stall.)

Make sure the sprocket doesn't wobble from side to side as it spins, & adjust the tensioner to feed the chain straight onto the sprocket.
 
wayne z

wayne z

Active Member
Dec 5, 2010
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Are you sure the engine isn't running rich?. They will sputter and pop and misfire with a sorta even rythem. This would be commonly referred to as 4-stroking.

If it pops intermittently, and mostly when you add throttle, it might be too lean.

Try adding a little choke while riding, and see if it gets better or worse, to help diagnose the problem.
 
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bikerpeter

New Member
Nov 30, 2010
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Idaho
It might be too rich, but I turned the air/fuel valve almost all the way in, so barely any air is getting into it, and its running better, but still not super good.
 
wayne z

wayne z

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Dec 5, 2010
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adding choke makes it richer. If it runs better with some choke, you are running too lean. These engines are useually set up from the factory too rich.
 
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mbuna420

New Member
Oct 9, 2010
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I also just changed over to the 100-1 amsoil and that seemed to make it a little worse. I found a place that sells ethanol free gas so I will be mixing that up from now on, should that blow out any ethanol build up if there is any? I saw it some where but could not find it in the search function recently; which way do you move the clip to make it leaner? My plug is gapped at about twenty eight hundredths and looks about right from what I can tell. Thanks for the help seemed like similar problems so I asked here but thinking of starting my own thread though if I can't get it figured out with these ideas thanks and peace out
 
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wayne z

wayne z

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Dec 5, 2010
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Nougat said:
A bit about the choke:

On the NT carb (with a choke lever on the right side by the air cleaner), the choke is a restrictor plate over the carb intake. This reduces the air coming in, which will make the mix of air/fuel richer - but the less air also causes less fuel to be drawn up from the bowl, so the effectiveness of this kind of choke has its limits.

On the CNS carb, where the choke pull is on the carb top (either with a handle right there, or with a remote handle at the end of a cable), the choke allows more fuel into the bowl than the needle valve would normally allow. There's no restriction in air at the intake, just more fuel into the mix. This kind of choke is more effective than the air restriction kind.
Click to expand...
I disagree with that. If you restrict the air, there is a strong vaccum in the carb body, gotta suck a LOT more fuel with high vaccum and very restricted air .
The cable pull is not a choke, but an special enrichening jet. They only work good with the throttle nearly closed. Hardly work at all with throttle open.

It's not possible to totaly flood an engine with an enrichening jet, whereas with a plate choke, if used enough while cranking the engine, can flood an engine until raw fuel is spitting out the exhaust.
If you use the plate choke just a little too much, the plug easily gets wet and won't fire.
Nearly impossible with the enrichening system.
 
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bikerpeter

New Member
Nov 30, 2010
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Idaho
Ok, so while I was on a trip to San Francisco with my church, my dad put the carb from an old 66cc motor onto the 50cc motor i have on my bike now. (the 66cc engines are illegal here.) He said it was running way better, but I have to leave the choke on more than half way, so more air is getting in. Unless that is less choke? lol. So more air is getting in, and when I have the choke on, and less air going in, it dies. So I don't know why it is doing that, and if Ic an even use a 66cc engine carb on a 50cc engine, which is what i have now on the bike.

I'm getting probably around 25mph on it now, rather than the 15 I got with the old normal carb that came with the 50cc engine. So I have a carb on the 50cc engine that came from a 66cc engine.
 
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Goat Herder

Goat Herder

Gutter Rider
Apr 28, 2008
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Oil has viscosity to it. More oil means the thicker viscosity has to go through a tiny jet in the carb. This in turn leans out your fuel to air mixture as a result. Less oil mixed with the gas means a thinner viscosity to go through a tiny jet. This in turn you will get more fuel introduced into your fuel to air mix. Running richer on fuel.

http://en.wikipedia.org/wiki/Viscosity
 
Goat Herder

Goat Herder

Gutter Rider
Apr 28, 2008
6,237
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Raising the clip on your carb body fuel metering rod will lean the carb out. Lowering the clip will richen it. If this adjustment is not enough you may need to go to a smaller jet on the carb.

Go over your carb manifold connections @ the carb and motor you do not want any vacuum leaks. As every adjustment you may do will be in vein other wise.


Do plug chops observe what color your spark plug is. A bit of a dark tan color on the side of chocolate in color is what you want the plug to look like.
 
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